(a) Field of the Invention
The present invention relates to a communication method and apparatus in a network environment in which dual connectivity is available.
(b) Description of the Related Art
In 3rd Generation Partnership Project (3GPP) Long Term Evolution (LTE), in an environment in which small cells are densely disposed in a multi-layer in a macro cell-based cellular network, in order to increase capacity of a wireless network through close cooperation between a macro base station and a small base station, standardization work of small cell enhancement technology has been performed. Objects of small cell enhancement technology when discussing 3GPP are to receive sharply increasing traffic, to efficiently manage mobility, and to secure coverage essential for mobile communication by increasing spectrum efficiency per unit area by disposing small cells at a high density. In order to achieve such an object, a 3GPP Radio Access Network (RAN) has been under discussion regarding requirements and a scenario for enhancing a small cell in Evolved-Universal Terrestrial Radio Access (E-UTRA) and an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN). At a RAN conference in December of 2012 a superordinate layer Study Item (SI) and a physical layer for enhancing a small cell were approved.
A 3GPP defined the following three scenarios in consideration of disposition, spectrum, and traffic of a small cell and compatibility with a previous specification in order to improve a small cell of a cellular network. The 3GPP discusses a technical issue and solution for three scenarios. The first scenario is one in which a macro cell and a small cell use the same frequency in a structure in which the macro cell and the small cell are overlapped. The second scenario is one in which a macro cell and a small cell use different frequencies in a structure in which the macro cell and the small cell are overlapped. The third scenario is one in which only small cells are disposed in a structure in which a macro cell and a small cell are not overlapped.
In a cellular network, communication technology that can support the first to third scenarios for enhancing a small cell is needed.
The above information disclosed in this Background section is only for enhancement of understanding of the background of the invention and therefore it may contain information that does not form the prior art that is already known in this country to a person of ordinary skill in the art.